The election of President and Vice President of the United States is an indirect election in which citizens of the United States who are registered to vote in one of the fifty states or Washington, D.C. cast ballots for a set of members of the U.S. Electoral College, known as electors. These electors then in turn cast direct votes, known as electoral votes, for President and Vice President of the United States. The candidate who receives an absolute majority of electoral votes for President or Vice President is then elected to that office. If no candidate receives an absolute majority for President, the House of Representatives chooses the President; if no one receives a majority for Vice President, then the Senate chooses the Vice President. The Electoral College and its procedure is established in the U.S. Constitution by Article II, Section 1, Clauses 2 and 4; and the Twelfth Amendment (which replaced Clause 3 after it was ratified in 1804).